Update System / Notifications tab

[mateumiralles]

Rename system / notifications sections' titles. Instead of "Ethical Metrics" and "Telegram" rename them to "External Notifications" and "Internal Notifications".

The copy of the sections should be updated too, explaining why those are external / internal (comes from the dappnode / external service ), and which notifications each provides.

Also implementing the "privacy toggle" in the external notifications fields (as done in the telegram token field), and replacing the internal notifications switch with the same as in external notifications.